Case Study
Chickerell 132kV/33kV
Capital replacement of coastal 132/33/11kV plant for SSEN
HMF Consultants completed feasibility and detailed design for Keltbray on SSEN's Chickerell substation capital schemes — replacing ageing outdoor plant at a coastal site and acting as Principal Designer.
Project Overview
Condition-driven replacement at a coastal grid substation
SSEN identified the poor condition of plant and equipment at Chickerell 132/33/11kV substation. Optioneering recommended a package of capital schemes to improve the Health Index of assets, future-proof the site, and reduce the risk of advanced ageing due to the substation's coastal location.
Scope of capital works:
- Replacement of the entire outdoor 33kV AIS switchgear
- Replace 2 x 45/90MVA 132/33kV Grid A1MT & A2MT transformers
- 2 x 33/0.415kV 1250kVA auxiliary earthing transformers
- 2 x 33kV neutral earthing resistors
- Installation of 1 x 90MVA 132/33kV A3MT transformer along with a new third bay
- Replace 4 x 132kV outdoor dead tank circuit breakers including associated civils
- Replace 4 x 132kV 2000A/40kA double break disconnector/earthing switches including associated civils
- Replace the existing LVAC
Project Facts
Key project metrics
132 / 33 / 11kV site
Multi-voltage capital replacement at Chickerell
3 x 132/33kV transformers
A1MT, A2MT replacement plus new A3MT 90MVA bay
Feasibility + detailed design
Full end-to-end design delivery for Keltbray
Key milestones 2024
Feasibility 14.08.2024 · Detailed design 06.11.2024
Project Highlights
Principal Designer delivery for Keltbray
- HMF has completed the feasibility design and detailed design
- Conduct regular design review meetings with SSE / Keltbray
- Conduct full end-to-end design for Keltbray, leading project coordination as Principal Designer
- Coordinate all design related to civil feasibility submission and cable design
Key Deliverables
Design packages delivered
- Designing of elevated 33kV switchroom
- Designing of transformer bunds of 3 x 132/33kV transformers and their auxiliary equipment
- MCP of 132kV and 33kV
- Feasibility design of 33kV cables
Key milestones
- Feasibility submission: 14.08.2024
- Expected detailed design submission: 06.11.2024
Engineering Challenges
Key engineering challenges
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Coastal accelerated ageing
Plant condition risk was heightened by the substation's coastal environment, requiring a comprehensive capital replacement package.
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Major plant change-out
Works included full outdoor 33kV AIS replacement, three 132/33kV transformers, four 132kV CBs and four disconnectors with civils.
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Elevated switchroom and bunds
Civil and electrical design had to align for the elevated 33kV switchroom and transformer bunds with auxiliary equipment.
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Multi-OEM coordination
Design integrated Siemens, GE, Tironi and Getra Transformers within one coherent site arrangement.
HMF Solution
Feasibility through detailed design under Principal Designer leadership
HMF completed both feasibility and detailed design, held regular reviews with SSE and Keltbray, and coordinated civil feasibility and cable design as Principal Designer.
Key packages included the elevated 33kV switchroom, transformer bunds for three 132/33kV units, MCP for 132kV and 33kV, and 33kV cable feasibility design.
Outcome & Impact
Future-proofing a coastal SSEN asset
Feasibility was submitted on 14.08.2024, with detailed design expected on 06.11.2024 — giving Keltbray and SSEN a clear path to construction-ready engineering.
The schemes improve asset Health Index, future-proof the site, and reduce coastal ageing risk for the Dorset network.
